Radiver Jonesta is the highest level Slayer Master, owner of the Slayer Guild and the only human in Carydwyn. Players need 115 Slayer and 130 Combat to get assignments from him. 24 Slayer reward points are awarded upon the completion of one of his tasks, 110 every 10th task, and 330 every 50th task. Radiver sells the Slayer cape to anyone who has achieved level 99 in Slayer and the True Skill mastery cape to anyone who had achieved level 120 in Slayer.

Unlike other slayer masters, Radiver is able to set different kinds of slayer challenges. Most of these challenges have a limit in which the player must complete the task. The table below shows the different challenges that a player may receive.

A popular theory among players was that Radiver is an elf. He confirmed that he is a human.

He and Kuradal seem to be lovers, since he sometimes mentions her in a romantic way. If you talk to Kuradal about him, she will show hate instead of love. This probably indicates a future quest which will involve these two.

He also appears to be great friends with Duradel, the father of Kuradal, as Duradel taught under Radiver. After While Guthix Sleeps, Radiver said he will have sworn vengeance for him. Lapalok appears to not like Radiver that much since he doesn't know too much about him.

Strangely enough, he is usually not smiling, but when you talk to him about Tasks, he will actually smile.

He shares the same exact model of Ali the Wise, possibly indicating that he is indeed Ali the Wise. It was confirmed by him that he and Ali the Wise are brothers. When the Ritual of Mahjarrat was released, he was corrected, and instead said they were sworn brothers. Jagex confirmed the "Brothers" part wasn't supposed to mean actual biological brothers.